• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.130-132
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• 2018

최근 1인 미디어의 확장과 맞물려 개인 차원에서의 영상편집이 활성화되고 있다. 인기 영상강의를 위주로 초보자들도 쉽게 접근할 수 있으나 여전히 많은 사람들이 영상제작을 어려워하고 있다. 특히 밝기, 대비 및 색 보정에서 어려움을 많이 겪는다. 전문적인 영상편집 툴의 경우 자동 보정 기능을 제공하고 있으나 파이널 컷의 경우 Apple 사의 맥 디바이스 환경을 구축해야 하는 문제, Adobe사 프로그램의 경우 완전 자동 기능 부재 및 무거운 연산처리 과정 및 유료화로 인한 접근성 저하, 기타 프로그램들의 경우 설치 접근성이 낮다는 단점이 있었다. 이에 본 연구에서는 클라우드 기반의 쉽고 빠른, 접근성을 높인 자동 영상보정 서비스를 제시하려 한다. 최종 단계의 클라우드 서비스에서는 흔들림 보정, 색 보정, 대비 보정, 명암 보정의 향상 기능과 컷 단위 인식, 신단위 인식, 객체 단위 인식의 서비스를 제공해야 한다는 결론에 도출하였다. 본 논문에서는 연구의 시작으로 클라우드 서비스 구축 및 OpenCV를 활용하여 프레임 별 영상 향상 알고리즘 구현을 시행하였다.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1046-1057
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• 2004

An image enhancement method using both homomorphic transformation and multiscale decomposition is proposed. The original image is first transformed to homomorphic domain by taking the logarithm, is then separated to multiscales. These multiscales are combined with weighting. The combined signal is exponentially transformed back into intensity domain. In homomorphic domain, the magnitude control of low frequency component make change the dynamic range, and the magnitude control of the other frequency components contribute to enhancement of the contrast. The "${\AA}$ trous" algorithm, which has a simple and efficient scheme, is used for multiscale decomposition. The performance of proposed method is verified by simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.12
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• pp.5127-5133
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• 2010

In this paper, an efficient contrast enhancement algorithm using histogram specification is proposed. Histogram equalization and its modified methods have been effective techniques for contrast enhancement. However, they often result in excessive contrast enhancement. Besides conventional histogram specification also has a problem to get the desired histogram. We propose a method that utilizes a simple high frequency filter to get the desired histogram. The proposed technique not only produces better visual results than conventional contrast enhancement techniques, but is also adaptively adjusted to the statistical characteristics of the image.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1681-1685
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• 2014

The visual quality of medical image is an important factor for diagnosis accuracy. Therefore, the methods to improve the quality of medical image have studied. Among them, frequency domain filter is very powerful method to impove the visual quality of image. In this paper, the X-ray medical image using optimized high-pass filter was improved edges. The result image was improved edge and contrast of flat area using optimized high frequency emphasis filter. At last, the result image is to minimize the noise using the minimum mean square error(MMSE) filter. As a result, the proposed method has enhanced contrast and edge of the image in the contrast of existing filters, with the noise canceling effect.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3265-3274
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• 1998

본 논문에서는 인간의 칼랄 인식 특성인 명도, 채도 및 색조의 관계를 학습시킨 신경회로망을 이용하여 열화된 영상의 채도 부분을 향상하는 칼라영상향상법으 제안하였다. 제안한 방법은 우선 표준영상으로부터 여러 단계 열화된 영상들로부터 얻은 다양한 명도, 채도 및 색조의 관계를 신경회로망의 입력으로 하고 표준영상의 채도를 목표차로 해서 신경회로망을 학습시킨다. 그리고 이렇게 학습된 신경회로망에 열화된 영상의 명도, 채도, 색조 그리고 향상시킨 명도를 입력하면 향상된 채도를 얻을 수 있는 칼라영상향상방법이다. 본 논문에서는 제안한 방법이 기존의 칼라영상향상법에서 가장 문제가 되었던 영상 향상 시 칼라범위를 초과하는 문제와 채도 향상비의 인위적 선택문제를 해결하고 채도의 대비를 향상시켜 선명한 영상을 얻을 수 있는 방법임을 밝혔다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.3
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• pp.52-59
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• 2009

In general, methods based on histogram or a correction of gamma curve are usually utilized to enhance the contrast of captured image in the dark scene. These methods are efficient to enhance the contrast globally, however, they locally induced the low quality of image. Recently, to resolve the problem, the multi-scaled refiner algorithm improving the contrast with locally averaged lightness is proposed. However, estimating the locally averaged lightness, if there is the object with a high saturated color, the color distortion might be induced by the color of object. Thus, in this paper, the dominant chromaticity of image is estimated to correct the locally averaged lightness in multi-scaled retinex algorithm. Because the average chromaticity of image includes the chromaticity of illumination, the dominant chromaticity is estimated with dividing the average chromaticity of image by the estimated chromaticity of illumination from highlight region. In addition, to improve the lower chroma by multi-scaled retinex algorithm generally, the chroma was compensated preserving the hue in the CIELAB color space.

• Journal of Broadcast Engineering
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• v.19 no.1
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• pp.96-108
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• 2014

In case of contrast of the image enhancement by using the conventional histogram equalization, over-enhancement, false contouring and distortion such as the details disappearance of the image occurs due to the excessive brightness change. Especially, these distortion appears when the brightness distribution is concentrated in a particular brightness level. In order to solve these problems, improved histogram equalization methods to transform the input histogram by clipping using threshold have been proposed, but contrast enhancement effect is reduced because it does not consider the characteristics of the input image's histogram to apply the same threshold for the entire histogram, and unnatural image is obtained because it does not retain the characteristics of the image. In this paper, to solve the problems of existing methods, we propose new equalization method that suppress excessive brightness changes by applying to the differential compression according to the histogram frequency, and maintain the characteristics of the input image. In addition, we propose a more effectively method to improve contrast by controlling the strength of the compression ratio depending on the characteristics of the input image.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.283-286
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• 2014

X-ray 영상의 경우 검은 배경으로 인해 기존의 히스토그램 평활화를 사용하여 대비비를 향상 시킬 경우 문제가 발생한다. 전역 히스토그램 평활화의 경우 영상의 특징을 고려하지 않은 채 전체적으로 히스토그램 평활화가 이루어지기 때문에 부분적인 명암값을 개선시키기 어렵다. BBHE(Bright Preserving Bi-Histogram Equalization)과 DSIHE(Dualistic Sub-Image Histogram Equalization)과 같은 영역별 히스토그램 평활화의 경우 X-ray 사진특성상 검은 배경으로 인하여 히스토그램 평활화를 적용해도 원하는 대비비를 얻기 힘들며 부분적으로 왜곡이 발생한다. 이러한 문제를 해결하기 위해 본 논문에서는 영상의 히스토그램을 통해 배경 정보를 파악하여 밝기 영역을 나눈 후 히스토그램 평활화를 진행함으로써 X-ray 사진의 대비비를 효율적으로 향상시킨다.

• Journal of Broadcast Engineering
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• v.15 no.3
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• pp.368-379
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• 2010

As high-definition video is broadly used in various system such as broadcast system and digital camcorder the proper method in order to improve the quality of high-definition video is needed. In this paper, we propose an efficient method to improve color and contrast of high-definition video. In order to apply the image enhancement method to high-definition video, scale-down video of high-definition video is used and the parameter for image enhancement method is computed from small size video. To enhance the color of high-definition video, we apply color constancy method. First, we separate the video into several scenes by cut detection method. Then, we apply color constancy to each scene with same parameter. To improve the contrast of high-definition video, we use union of original image and histogram equalized image, and weight is calculated based on sorting of histogram bins. Finally, the performance of proposed method is demonstrated in experiment section.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.2
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• pp.104-111
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• 2010

This paper presents an adaptive image enhancement method using the spatial frequency property in the DCT(discrete cosine transform) compressed domain. The dc coefficients, the illumination components of image, are adjusted to compress the dynamic range of image, and the ac coefficients are modified to enhance the contrast by using the human visual system(HVS) and the spatial frequency property. The ac coefficients are separated into vertical direction, horizontal direction, and mixed spatial frequency components, and adaptively modified to minimize the block artifacts that possibly occur in the image enhancement. The proposed method using dynamic range compression and adaptive contrast enhancement shows the advanced performance without the block artifact compared with existing method.